1. Field of the Invention
The present invention generally relates to a packet processing system, and more specifically, to a system and method for processing packets.
2. Description of Related Art
Internet has brought about significant impact on human life. Nowadays, the computer networking techniques are evolving from telecommunications connection of physical wired network into telecommunication connection of wireless network, allowing people to surf the Internet freely without being restricted to the physical network wiring.
However, the transmission quality of the wireless network is determined by the transmission media, such as far infrared rays or electromagnetic waves, the environment in which the users are located, such as the distance between base stations, obstructions in the signal transmission route and the material of the obstruction, and other factors.
The above described problems have serious impact on the customers of the wireless network accessing the multicast service provided by the server. The multicast service usually adopts the user datagram protocol (UDP), which is connectionless oriented. The server that uses the above mentioned communications protocol is dedicated to sending multimedia packets only and is not responsible for guaranteeing that the multimedia packets are successfully received by the client terminal (members in the multicast group established by the multicast service). In addition, the IEEE 802.11 wireless communications protocol does not provide any mechanism to ensure clients in the multicast group to successfully receive multicast packets. Thus, when the client is located in a place with weak wireless signals but intends to use a multimedia multicast service such as Video on Demand (VOD), video conference, or distant learning, factors such as weak wireless signals may cause the client a failure in receiving the multimedia multicast packets transmitted to the client by a multimedia server, thus leading to a low quality viewing of such multimedia program on the client side.
In order to allow all the clients to receive multicast packets, in the modern technology, the multicast packet transmission mode of an Access Point (AP) selects the lowest transmission rate of all the supported speeds as the multicast packet transmission rate. In this method, the lowest transmission rate is more tolerant to greater noise interference and has a longer transmission distance. Therefore, the probability that all clients in the multicast group successfully receive multicast packets can be increased. However, many factors must be taken into consideration in terms of determining whether a network packet can be successfully delivered to the client. The method described herein is still unable to ensure proper delivery of multicast packets to the client as well as the multimedia broadcasting quality on the client side.
In addition, the client with the slowest transmission rate in a multicast group puts a burden on the overall transmission rate of the multicast group of the Access Point. This causes other clients to leave a large amount of bandwidths idle due to the presence of the client having the slowest transmission rate, even if they have a large amount of bandwidths available for multimedia multicast packet transmission. Further, since a slower transmission rate is selected, the viewing quality of the multimedia file is then lowered. Accordingly, it has become a highly urgent issue to overcome the above described disadvantages.